Rapid inflation systems are currently used in various applications, but have achieved significant commercial recognition in the aviation industry in connection with the rapid inflation of evacuation slides and liferafts which are deployed in emergencies. Typical rapid inflation systems use pressurized primary gas to induce or aspirate a secondary gas or ambient air to combine with the pressurized gas so as to rapidly inflate an inflatable structure such as an evacuation slide. Specifically, in such aspirator devices, a pressurized primary gas is rapidly introduced into the aspirator assembly through a nozzle arrangement. This rapid introduction of pressurized primary gas in combination with certain design of a mixing area or tube creates a partial vacuum within the aspirator assembly, and thereby entrains a secondary gas or ambient air to enter the aspirator assembly through inlet check valves provided for that purpose. Once inside the aspirator assembly, the ambient air passes through a converging region of the aspirator assembly, through a transition zone, and mixes with the primary gas in a mixing region to generate a combined air-gas flow mixture. This combined air-gas flow exits the aspirator assembly through a discharge region of the tube which is normally disposed within an inflatable structure. Thus, the aspirator assembly uses a small volume of pressurized primary gas to entrain a relatively large volume of a secondary gas or ambient air to inflate an inflatable structure. The efficiency of the aspirator assembly is often measured by its "mass-flow ratio," which is a ratio of the volume of primary gas used by the aspirator assembly to the volume of secondary gas or ambient air entrained by the aspirator assembly.
The prior art references disclose aspirator assemblies which operate generally as described hereinabove, but which suffer from a number of drawbacks. It is known in the art that the mass-flow ratio of an aspirator assembly depends in large part on the location of the introduction of the primary gas into the aspirator assembly and location of the nozzle jets with respect to the transition zone between the converging and mixing regions of the mixing tube. While these prior art devices achieve sufficient entrainment of ambient air to rapidly inflate evacuation slides and liferafts in emergencies, none of the devices disclose a design capable of providing adjustments, so as to optimally locate and to lock such optimal position of the transition zone of the mixing tube with respect to the nozzle jet assembly.
As stated above, aspirator assemblies are typically used in high-stress emergency situations. It is not uncommon for the inlet check valves to be inadvertently pushed open by passengers' fingers, aircraft debris, etc. after the evacuation slide or raft has been inflated. This can cause the evacuation slide or raft to deflate, compromising its safety and effectiveness. It is known in the prior art to provide safety features preventing undesirable accidental deflation of the emergency evacuation structures; design of such features, however, has been complicated, making them expensive to maintain and manufacture.
Finally, due to the probability of widespread commercial application of aspirator assemblies, those aspirators which are most easily manufactured and assembled are most desirable. The prior art devices often employ a multiple-piece housing design in which the major components of the device are either welded or bolted together, which complicates manufacture of the device.
It is, therefore, an object of the present invention to provide an aspirator assembly having an increased efficiency leading to reduction of time required to inflate a given inflatable structure.
It is also an object of the present invention to provide an aspirator assembly having a selectively sealable inlet and, thereby providing the ability to alternatively permit or prevent opening of the aspirator inlet check valve.
It is also an object of the present invention to provide an aspirator assembly having a simplified assembly process, thereby reducing manufacturing time, manufacturing errors, and manufacturing inefficiencies.